Hydraulic steering

Abstract

The invention concerns a hydraulic steering with a steering motor arrangement, a steering valve arrangement and a pressure supply comprising a first pump and a second pump. It is endeavoured to perform a change between the supplies by the pumps as unperceived as possible. For this purpose, the steering valve arrangement ( 4 ) is connected to the first pump ( 6 ) through a valve ( 8 ) with pressure compensation function and to the second pump ( 19 ) through a compensation valve ( 26 ).

1 . A hydraulic steering with a steering motor arrangement, a steering valve arrangement and a pressure supply comprising a first pump and a second pump, wherein the steering valve arrangement is connected to the first pump through a valve with pressure compensation function and to the second pump through a compensation valve.  
   
   
       2 . The steering according to  claim 1 , wherein the valve is made as a priority valve.  
   
   
       3 . The steering according to  claim 1 , wherein the valve is acted upon in the closing direction by the pressure at its outlet and in the opening direction by the force of a first spring and a load-sensing pressure ruling at the outlet of the steering valve arrangement, and the compensation valve is acted upon in the closing direction by the pressure at its outlet and in the opening direction by the force of a second spring and the load-sensing pressure, the first spring producing a larger force than the second spring.  
   
   
       4 . The steering according to  claim 3 , wherein the compensation valve ends between a first non-return valve opening in the direction of the steering valve arrangement and the steering valve arrangement in a pipe between the valve and the steering valve arrangement.  
   
   
       5 . The steering according to  claim 3 , wherein the compensation valve is connected to the first pump via a second non-return valve opening in the direction of the compensation valve.  
   
   
       6 . The steering according to  claim 1 , wherein the second pump has an electrical drive, the outlet of the second pump being connected to a hydraulic accumulator, the electrical drive being controlled in dependence of the pressure in said tank.  
   
   
       7 . The steering according to  claim 1 , wherein the steering valve arrangement comprises one single steering valve.  
   
   
       8 . The steering according to  claim 1 , wherein the steering valve arrangement comprises a primary steering valve and a secondary steering valve, the compensation valve being located between the second pump and the secondary steering valve.  
   
   
       9 . The steering according to  claim 8 , wherein a stop valve arrangement is provided that interrupts a connection between the first pump and the primary steering valve and releases a connection between the secondary steering valve and the steering motor arrangement in case of a fault.  
   
   
       10 . The steering according to  claim 8 , wherein the primary steering valve has a first load-sensing circuit acting upon the valve, and the secondary steering valve has a second load-sensing circuit acting upon the compensation valve.  
   
   
       11 . The steering according to  claim 8 , wherein the outlet of the secondary steering valve is connected via a pipe to the inlet of the primary steering valve, a stop valve being located in said inlet.  
   
   
       12 . The steering according to  claim 8 , wherein it may be provided that the outlet of the compensation valve is connected via a pipe to the inlet of the primary steering valve, the stop valve being located in said pipe.  
   
   
       13 . The steering according to  claim 9 , wherein the stop valve arrangement comprises a part, which is located between the valve and the primary steering valve.  
   
   
       14 . The steering according to  claim 9 , wherein the stop valve arrangement has several valve functions, which are combined in one single change-over valve.  
   
   
       15 . The steering according to  claim 14 , wherein the change-over valve is made as a slide valve.  
   
   
       16 . The steering according to  claim 1 , wherein the steering valve arrangement, the valve, the compensation valve and, in some cases, the stop valve arrangement are combined in one unit.  
   
   
       17 . The steering according to  claim 16 , wherein the unit is integrated in or flanged onto the steering motor arrangement.